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Title: Pressure-temperature effects on knock with iso-octane and propane at various compression ratios and intake temperatures

Abstract

Knock remains one of the main limitations for increased internal combustion engine efficiency. Recent trends in light-duty vehicles towards downsized, boosted engines increases the need for improving the understanding between fuel chemistry and thermodynamic effects contributing to knock. Previous studies have shown the importance of end-gas thermodynamic conditions on knock onset and behavior, with relationships to fuel chemistry illustrated. However, a complete understanding of how fuels allow access to higher engine loads and the governing physics behind end-gas knock under a wide range of thermodynamic conditions is still unclear. Experiments in this work improve this understanding with the use of three fuels (1) iso-octane, a low octane sensitivity (OS) fuel (2) a Co-Optima aromatic core fuel, which has similar research octane number (RON) yet significantly higher OS, and (3) propane, known for its knock resistance. Engine load sweeps are conducted with each fuel while maintaining a CA50 of 8 crank angle degrees after top dead center (°CA aTDCf). As load increases and knock onset is observed, spark is delayed to its knock limited spark advance (KLSA) allowing further increases in load until either one of two limits is reached; (1) CA50 retard limit (2) Peak cylinder pressure limit. Experiments aremore » conducted at 40°C and 90°C intake temperature and at two distinct compression ratios (rc) 9.2:1 and 13.6:1. Two-zone zero-dimensional simulations were performed in Chemkin to extract end-gas pressure and temperature conditions through the combustion process for each experimental condition of interest. CA50 response as a function of engine load is compared for all experimental conditions and fuels, and a pressure-temperature (PT) trajectory analysis is conducted using constant volume ignition delay contours to explain the behavior of each fuel.« less

Authors:
 [1]; ORCiD logo [1]; ORCiD logo [1];  [2]
  1. ORNL
  2. Lawrence Livermore National Laboratory (LLNL)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1649198
DOE Contract Number:  
AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: 2020 Spring Technical Meeting of the Central States Section of The Combustion Institute - Huntsville, Alabama, United States of America - 5/17/2020 8:00:00 AM-5/19/2020 8:00:00 AM
Country of Publication:
United States
Language:
English

Citation Formats

Dal Forno Chuahy, Flavio, Splitter, Derek, Boronat Colomer, Vicente, and Wagnon, Scott. Pressure-temperature effects on knock with iso-octane and propane at various compression ratios and intake temperatures. United States: N. p., 2020. Web.
Dal Forno Chuahy, Flavio, Splitter, Derek, Boronat Colomer, Vicente, & Wagnon, Scott. Pressure-temperature effects on knock with iso-octane and propane at various compression ratios and intake temperatures. United States.
Dal Forno Chuahy, Flavio, Splitter, Derek, Boronat Colomer, Vicente, and Wagnon, Scott. Mon . "Pressure-temperature effects on knock with iso-octane and propane at various compression ratios and intake temperatures". United States. https://www.osti.gov/servlets/purl/1649198.
@article{osti_1649198,
title = {Pressure-temperature effects on knock with iso-octane and propane at various compression ratios and intake temperatures},
author = {Dal Forno Chuahy, Flavio and Splitter, Derek and Boronat Colomer, Vicente and Wagnon, Scott},
abstractNote = {Knock remains one of the main limitations for increased internal combustion engine efficiency. Recent trends in light-duty vehicles towards downsized, boosted engines increases the need for improving the understanding between fuel chemistry and thermodynamic effects contributing to knock. Previous studies have shown the importance of end-gas thermodynamic conditions on knock onset and behavior, with relationships to fuel chemistry illustrated. However, a complete understanding of how fuels allow access to higher engine loads and the governing physics behind end-gas knock under a wide range of thermodynamic conditions is still unclear. Experiments in this work improve this understanding with the use of three fuels (1) iso-octane, a low octane sensitivity (OS) fuel (2) a Co-Optima aromatic core fuel, which has similar research octane number (RON) yet significantly higher OS, and (3) propane, known for its knock resistance. Engine load sweeps are conducted with each fuel while maintaining a CA50 of 8 crank angle degrees after top dead center (°CA aTDCf). As load increases and knock onset is observed, spark is delayed to its knock limited spark advance (KLSA) allowing further increases in load until either one of two limits is reached; (1) CA50 retard limit (2) Peak cylinder pressure limit. Experiments are conducted at 40°C and 90°C intake temperature and at two distinct compression ratios (rc) 9.2:1 and 13.6:1. Two-zone zero-dimensional simulations were performed in Chemkin to extract end-gas pressure and temperature conditions through the combustion process for each experimental condition of interest. CA50 response as a function of engine load is compared for all experimental conditions and fuels, and a pressure-temperature (PT) trajectory analysis is conducted using constant volume ignition delay contours to explain the behavior of each fuel.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2020},
month = {6}
}

Conference:
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